Gaze detection of a person from an image is very effective since a gazing area of the subject person is estimated without causing a subject person to wear a specific apparatus. However, the gaze direction depends not only on the movement of the eyeballs, but also on the posture of the head of the subject person, and the image pattern near the iris changes variously not only by the posture of the head and the direction of the eyeballs, but also by the facial configuration of individuals, which is a difficult subject to solve.
In a gaze detection method disclosed in Japanese Application Kokai 2005-13752, the shape of the iris of the subject person is approximated into an ellipse, and the gaze direction is detected on the basis of the parameter of the ellipse. However, since the change in appearance of the iris due to the posture of the head and the change in appearance of the iris due to the actual movement of the eyeballs cannot be discriminated, the gaze direction cannot be detected according to a given posture of the head.
In a gaze detection method disclosed in Japanese Patent No. 3790680, pattern dictionaries by the direction of pupils are prepared in advance, and the gaze direction is detected by matching between the dictionaries and the pupil patterns of an input image. However, in order to detect the gaze direction with high degree of accuracy, it is necessary to learn various gaze direction patterns in advance.
In a gaze detection method disclosed in Japanese Application Kokai 2004-255074, the shape of the eyeball is estimated from an image taken by a stereo camera, then, a contact plane with respect to the eyeball at the center of the iris is estimated, and then the normal line of the contact plane is detected as the gaze. However, this method has a problem that calibration of the stereo camera is necessary, and hence a large scale of system is required.
As described above, the related art has a problem that the gaze cannot be detected from a given posture of the head with a single-lens camera unless calibration or learning of the pattern by directions of the pupils is performed in advance.
In order to solve the problems in the related art as described above, it is an object of the invention to provide a gaze detection apparatus for estimating the gaze direction from a given posture of the head with a single-lens camera without necessity of calibration and learning of the pattern by directions of the pupils in advance, and a method of the same.